I thought they're trying to actively block it as it allowed people to watch without ads.

Pihole + uBlock Origin, I never see ads on Twitch or YouTube. I only see sponsors and affiliates in YT (and I guess Twitch as well, not watching much Twitch tbh). Which usually don't work in EU the one time I am interested (LTT...)

youtube-dl (and forks) work with twitch (using mpv). I've never understood why people use streamlink instead.

Can youtube-dl work with live?

Last I checked, ytdl when used standalone has poor behavior with live: it will fetch the live stream, but if ytdl gets up to "current time", it considers the live stream complete instead of continuing to capture it in real-time.

This may or may not affect using mpv's ytdl integration (where mpv internally calls ytdl to obtain a stream).